Temperature control system for electromechanical oscillators



Jan. 10, 1933. GEBHARD 1,893,666

TEMPERATURE CONTROL SYSTEM FOR ELECTROMECHANICAL OSCILLATORS Filed May 20, 1950 4 Sheets-Sheet l Jan. 10, 1933. 1.. A GEBHARD 1,893,666

TEMPERATURE CONTROL SYSTEM FOR ELECTROMECHANICAL OSCILLATORS Filed May 20. 1930 4 Sheets-Sheet 2 v i 3 INVENTOR.

h BY #MM ATTORNEY.

Jan. 10, 1933. L. A. GEBHARD 1,893,666

TEMPERATURE CONTROL SYSTEM FOR ELECTROMECHANICAL OSGILLATORS Filed May 20, 1930 4 Sheets-Sheet 5 INVENTOR. 904443: a. Qmfifiovu),

BY M N A TTORNEY Jan. 10, 1933. 1.. A. GEBHARD 1,893,666

TEMPERATURE CONTROL SYSTEM FOR ELECTROMECHANICAL OSCILLATORS Filed May 20, 1950 4 Sheets-Sheet 4 Iain-i I III I H01 llfil.

I N V EN TOR. a $456M), IAM LAENQ L ATTORNEY conditions for. the

1.445 ing system.

i Patented Jan. 10; 1933 "i62mmST PATENT orrlce I Louisa; GEBIIARD, or WASHINGTON; DISTRICT 01* COLUMBIA, AQSSIGNOR TO WIRED V RADIO, me, or NEW Ycnx, n. Y.

, A CORPORATION OF DELAWARE TEMPERATURE CONTROL SYSTEM FGTt ELECTROMECHANIGAL OSCILLATORS application filed May 20,

invention relates broadly to constant r,, .;frequenoy-control apparatus and more par- I ticularly to an apparatus for maintaining a multiplicity of electromechanical oscillators '5 under constant conditions.

One of the objects of my invention to provide a construction of cabinet apparatus in Vwhich a multiplicity of electromechanical oscillators may beymainta'ined under constant frequency control of signaling systems. Another object of myinvention is to pro rvidea construction of mounting for a multiplicity of electromechanical oscillators in 13 which facilities are provided for the replacement of any one of the electromechanical oscillators and the maintenance of all of the oscillators'under constant conditions for the accurate fixing of;v frequency in a signaling 2o system.

Still-another object .of my invention is to provide a construction of cabinet for the mounting of a multiplicity-of electromechanical oscillators ina manner in which the os- :5 cillators may be maintained at constant temperature for the accurate fixing of frequency in a. signaling system. i

YA further object of my invention is to provide a construction of mounting for a he 1180 'quency controljapparatus wherein a multi 'plicity of electromechanical oscillators may be simultaneously inserted or withdrawn from atemperature control cabinet structure within which the electromechanical oscillatorsare subjected to constant conditions for i the frequency control of signaling circuits.

v A still further object of my invention is to provide a construction of heat conductive support for a multiplicity of electromechanical r40 oscillator mountings the support having such characteristics that temperature conditions 7 maybe equalized at .each'of the electromechanical oscillator mountings for the accurate fixing of frequency inthe. circuits of a signal- ,Other and further objects of my invention reside in the arrangementof frequency control apparatus as set forth more fully in the -specificationhereinafter following by refera once to the accompanying drawings, in which 1930. Serial No. 454,169.

' it is essential that the oscillator elements be maintained under constant conditions of temperature in order to assure theproper frequency stability of the transmitting circuits. Under certain conditions in radio transmitters it is necessary to quickly shift from one frequency to. another and in some instances provision must be made for operation upon a relatively large number of different frequencies. It is essential to have the oscillator elements controlled at constant temperature with provision for selectively connecting any one of the oscillator elements in the frequency control circuit.

In illustrating my invention I have shown mountings for piezo electric crystal elements which are supported within a cabinet structure insuch' manner that the temperature thereof maybe accurately controlled. While I have shown piezo electric crystal elements used asfrequency determining means it will be understood that magnetostriction devices may be employed or other forms of constant frequency controlled devices may be arranged in the mounting which I illustrate herein. If piezo electric crystals are employed these crystals may be ground to a definite working temperature which has been established in the practice of the United States Navy at centigrade. The system of crystals, however, must be arranged so that if a crystal fails in service it may be replaced by a spare which is kept on hand. This makes it essential that all crystals be ground for the same temperature, namely 50 C. and be held accurately to this temperature. Very little temperature gradient; from one crystal" to another as well to the outside of the cabinet structure.

metal member -"extending from-the outside wall 9 of the cabinet structure serve to carry the motor 25 in a laterally extending support designated at; 48. The: motor 2 5 drives the heat insulate'd shaft 24 which 'connects to fan 23.

'The heat insulation 24'is provided in order to. prevent conduction of heat from the inside A guide ring 26 encircles the shaft 24 and prevents the stirring up of the air in thespace 11 between the layers 91and 10.

to the heater 21 and thermostat 17 as shown M31 in Fig, 4'." 'These connections, together ,withtheconnections for the electromechanical oscillators are so arranged that a minimum amount of metal passes through the layers 9, 1O"a-nd 11 as shown for example by the insulated bushing 32 and conductive 32a which extends therethrough. By thisarrangement very little heat is conducted from the inside to the outside of the cabinet or vice versa. That is, the effect of theambient temperature is minimlzed. The

7 air circulation is shown by the arrows. By

l reversing*thedirection of rotation of the fan 23'the direction of the air currents may be reversed'ifitf is so desired. Connection from the"switch structureb by which a particular electromechanical oscillator may be selected is established outside of the cabinet structure by an arrangement of jacks 34 which I panel 7. The rotation of switch 5 is controlled leadfrom theexteri'or of the cabinet structure and. whichreceive the blocks 33 carried by the insulated panel 4;. As the support for the electromechanical oscillators is moved into the cabinet structure, connection is completed between plugs-33 and jacks 34.

In'order'thatthe temperature of the casting comprising the horizontally extending shelves 2Qand the upright portion 3 may be checked, a right angle thermometer 35 is inserted into the aperture 36 in theenlargedportion of the lowest shelf 2 of the casting. The uprightportion of this thermometer is zarranged in back of a window in the front panel 41 of the transmitter apparatus so as to makethe scale ofithe thermometer visible The thermometer is supported from panel 7 by means of sprmg'chp's 37 and 37 carried by l through insulated shaft 33 by means of knob 39 which projects outside of the front panel 41 of the transmitter. The knob 39 may be provided with a dial '40 thereon calibrated to indicate the particular electromechanical oscillatorwhich is connected within the control circuit for any given position of the knob 39. The panel 41 is hingedto the frame of the transmitter and may be swung outwardly therefrom, the dial 40 and knob 39 clearing the'panel 41 by reason of the apertux-e49 in the panel 41. A disk 43 is positioned behind the dial 40 and serves to close the gap in the front of the panel in coopera- 7 tionwith the bezelring 42. The opening of the door or hinged panel 41 enables access to be had to the screws 12a for the removal of the frame which carries the several electromechanical oscillators from thecabinet structure or the insertion'of the frame into the cabinet structure. The closing of thehinged panel 41 and the latching thereof in closed position by means of latch 51 shown in Fig.

2 enables the entire frequency control apparatus to be mounted in therear of the front panel structure of a radio transmitter. Bracket members 52 are provided for supporting the cabinet structure from the framework 53 of the transmitter. 1 v

The electromechanical oscillators such as piezo electric crystals in the several mountings indicated at 1 are each connected by. different operating characteristics. In the case of piezo electric crystals the crystals are each ground to different frequency characteristics and the selector switch serves to pick out the desired piezo electric crystal which is to be connected in the control circuit. Proper 1ndications are provided on dial 40 so that the operator is informed as to which piezo electric crystal isselected for operation.

By providing the single heat conductive casting, conduction of heat currents from any one of the electromechanical oscillation is fa;

cilitatedand the temperature thus equalized and maintainedconstant. It will be understood that when the electromechanical oscillators are in the'form of'piezo electric crystals that each'crystal has its lower face in contact with the lower conductive heat element 1a of the housing 1 so that heat generated by the rapid mechanical vibration of the crystal is conducted away from the crystal conductively through the horizontally extending shelves 2. Or vice versa heat which is impressed upon the mass formed by the metallic shelves 2 and upright portion 3 is conveyed to each piez'o electric crystal element through the conductive end plate 1a of the housing 1. It will be realized that the relatively large mass of metal comprising the casting consisting of horizontally extending shelves 2 and upright portion 3 tends to remain at constant temperature so that maintenance of the temperature within the cabinet structure at a constantvalue serves to maintain the temperature throughout the mass of metal in the casting 23 at constant value. Any tendency ofthe temperature ad- 7. multiple frequency control apparatus comprising a temperature controlled box like cabinet structure, open at one side, a slidably removable Wall member for the open side of sa1d cabinet, structure servmg as a closure when 1n place, a frame carried by said Wall "member, said frame comprising a single cast- 7 ing of heat material of high heat conductivity including a multiplicity of laterally extending shelf-like portions integrally connected by a vertically extending Web portion an electromechanical oscillator holder individual to eachof said laterally'extending shelf-like portionsysaid casting being disposed in the path of circulating air currents Within said cabinet structure at substantially constant temperature, and electrically selective means for rendering any one of said eletromechanicaloscillator -mountings effective for frequency control.

8. A frequency control apparatus compris- 'ing a temperature controlled box like cabinet structure, a slidably removable end Wall for V saidcabinet'structure, a casting of high heat conductivity mounted interiorly of said removable end Wall, said casting comprising a multiplicity of laterally extending heat conductive portions extendingintegrally from each side of a'centrally'disposed Web portion for forming a multiplicity of shelf-like portions, a plurality of electromechanical oscili i lator holders adapted to be removably carried by each of the shelf-like portions of said casting, means for subjecting said casting 35 constant temperature, and selector means for to circulating air currents of substantially rendering any one of said electromechanical I oscillator mountings electrically effective.

9. A multiple frequency control apparatus comprising a temperature controlled box like cabinet structure, a Wall member slidably insertable into or removable from one side of said cabinet structure, a casting of high heat conductivity supported by said Wall member, said casting including a vertically extending web and a multiplicity of laterally extending integrallyfconnected shelf-like portions projecting in opposite directions therefrom,

7 electromechanical oscillator housings removably mounted uponeach of said shelf-like portions, means for subjecting said casting and the electromechanicaloscillator housings thereon to circulating air currents of substantially constant temperature, and selector means operative from the exterior of said cabinet structure for rendering any one of i the electromechanical oscillator housings electrically eifective.

-10. Frequency control apparatus comprising a'temperature controlled box like cabinet structure having one end thereof slidably separable therefrom, a frame supported by theseparable end of said cabinet'structure, said frame including a single casting having a vertically extending web and a multiplicity cillator housings therein eletrically effective.

LOUIS A. GEBHARD. 

